Much of today's building construction consists of a building frame constructed of steel, concrete, or wood, and walls constructed of concrete masonry units, brick, precast concrete elements or any other segments mortared together.
For the purposes of this specification, the present invention will be described as being applicable to the attachment of walls prepared using concrete masonry units, which will also be referred to herein as masonry walls, to a steel frame building. However, it is to be understood that the device and method of the present invention are applicable to buildings having walls and frames constructed of other materials commonly used in the construction industry.
The role that the wall serves in a building is usually one or more of the following:    1. The wall can be a load bearing wall. In this case the wall is supporting part of the frame for gravity loads.    2. The wall can be a shear wall. In this case the wall provides resistance to the horizontal loads applied on the building, parallel to the direction of the wall.    3. The wall can be non-structural, such as when it is the outer skin of the building, or an interior wall.
In all of these roles, the wall itself may be supported for gravity loads by the foundation, or by the building's frame, or combinations thereof.
The present invention deals with the transfer of horizontal forces between the building frame and the walls. The causes for these forces are usually wind, seismic loads, soil pressure, and other factors known to those skilled in the art.
There are two types of horizontal forces transferred between the wall and the building frame:    1. Lateral forces perpendicular to the wall (transverse forces).    2. Longitudinal (shear) forces, parallel to the wall.
Generally, the wall is always connected to the frame so as to transfer the transverse forces between the wall and the building's frame. In the case when the wall is a shear wall, it is connected to the frame so as to transfer also the longitudinal shear forces between the wall and the building's frame.
Connectors, generally made of steel plate, are used to ensure the full transfer of horizontal forces between the masonry wall and the steel frame. The connectors are generally made of flat, or corrugated, but mostly galvanized, steel plate. The connectors are embedded in the masonry wall mortar beds on one end and hooked at their other end to a vertical sliding rail attached to the steel frame. The connectors are placed at frequent intervals, so as not to incur high secondary stress in the masonry wall or the steel frame. The present invention will deal with a device for, and method of, providing adequate steel connectors to transfer the applied horizontal forces.
The prior art provides basically two types of connectors:    1. A fixed length plate embedded in the masonry wall mortar bed, and/or embedded in fully grouted cells. The plate is hooked into a vertical slotted channel, the slotted channel generally being welded to the web of a steel beam which is parallel to the wall. The plate can be flat, corrugated and can have its embedded end hooked.    2. A fixed length plate embedded in the masonry wall mortar bed and/or embedded in fully grouted cells. The plate is hooked around the far edge of the beam or the truss flange. The plate can be flat, corrugated and can have its embedded end hooked.
The prior art connectors have several significant drawbacks:    1. The embedded part of the connector bar may end in the hollow cells of the masonry units. Thus, in order to provide adequate anchorage, the cells mut be fully grouted above and below the connector. The grouting is disruptive to the progress of wall construction, and is costly. The grouting operation requires additional quality control measures. If the grouting of the top cells is not done continuously with that of the bottom cells, the embedment will end up in what is known as a cold joint. The connector embedment is weakened by a cold joint because of the shrinkage of the separately poured portions of grout. As will be described later, the masonry connector system of the present invention corrects this condition by introducing an anchor bar member which is attached to a hook bar member. Thus, the connector will resist the applied forces in all situations, even when using a hollow masonry wall, using mortar only and without the need for grouting.    2. When the hook end of a prior art connector bar is “T-shaped to engage a slotted channel, it applies non-symmetrical forces on the channel, when in shear, which channel is not efficiently designed for such forces. In general, the prior art system is designed to resist very small forces, and the rail is designed to span a very short distance. The rail is typically a 5 or 6 inch long channel that is welded to the web of the beam. The present invention corrects this condition by providing a new connector bar hook end and a new sliding rail. The new system can economically resist bigger forces and span a longer distance, thus enabling the masonry connectors of the present invention to be attached to trusses as well as to beams, something the prior art did not provide for.    3. The prior art slotted channel is usually welded to the web of the beam. When connecting the wall to a sloped beam, the elevation of the slotted channel varies with the slope of the beam. The elevation of the connectors, which are embedded in the mortar bed between block courses, vary in steps corresponding to the block courses. Thus, in many cases, even if the short slotted channel accommodates the connector hook, it may not accommodate the additional clearance needed for the beam to deflect freely without bending the connector plate or introducing torsion in the beam. Many times the slot of the slotted channel falls against the solid wall of the cmu, not allowing the connector embedded in the mortar bed to be engaged. The masonry connector system of the present invention corrects this condition by introducing a new sliding rail that can be attached to the beam or joist so as to allow for a longer sliding length. It is not practical to install the slotted channel on an open web of a truss.    4. When the hook end of a prior art connector bar is “J” shaped, it hooks to the flange of a beam, truss or to any other steel member. This connection will be possible only if the flange of the steel member falls at the same elevation as the mortar bed of the masonry wall. This is mostly not the case, since even if designed for, the construction tolerances may cause such differences in those elevations. It is especially not the case when the steel member is sloped, as it is mostly in the roof. When successfully installed, this connection provides resistance to transverse force in one direction only. In addition, this does not allow the steel to deflect freely without bending the connector plate or introducing torsion in the steel. The masonry connector system of the present invention corrects this condition by introducing the same new method used for the beams (above), to be used in conjunction with the trusses, or other steel members where the vertical slotted channel cannot be attached.
Thus, there is a need to provide a new device for and method of connecting the masonry wall to the building steel. The present invention is designed to be more efficient, able to resist the actual loads applied on the building, and be consistent with the engineering concepts used in the structural design of the building. The present invention allows for attachment of walls to the building frame, using trusses as well as beams, which can produce a cost savings in the quantity of steel needed. The connecting devices embodied in the present invention allow for construction of masonry walls without the need for grouting between the cells.